gamma-ray burst jets: dynamics and interaction with the progenitor star davide lazzati, brian...
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![Page 1: Gamma-Ray Burst Jets: dynamics and interaction with the progenitor star Davide Lazzati, Brian Morsony, and Mitch Begelman JILA - University of Colorado](https://reader036.vdocument.in/reader036/viewer/2022062407/56649d255503460f949fc6a2/html5/thumbnails/1.jpg)
Gamma-Ray Burst Jets:
dynamics and interaction with the
progenitor star
Gamma-Ray Burst Jets:
dynamics and interaction with the
progenitor starDavide Lazzati, Brian Morsony, and Mitch
BegelmanJILA - University of Colorado
Davide Lazzati, Brian Morsony, and Mitch
BegelmanJILA - University of Colorado
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Evidence for SN association
Evidence for SN association
SN2003dhStanek et al. 2003Hjorth et al. 2003
SN1998bwGalama et al. 1998
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Phases of jet propagation
Phases of jet propagationConfined Jet Shock breakout
Shocked jet Unshocked jet
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I: confined jetI: confined jet
Jet head propagates under ram pressure equilibrium
No mixing between shocked jet and star material
Cocoon is over-pressured and drives shock into stellar material. Shock expands under Kompaneets approximation vsh~(pcocoon/star)1/2. Cocoon cools adiabatically (relativistic EOS).
Jet reacts to cocoon pressure with internal and ram pressure terms. Acceleration ~p-1/4.
Lazzati & Begelman 2005
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I: confined jetI: confined jetIn a monolithic jet the pressure scales with working surface
P~-1/2 Simulations show the monolithic approximation to be inaccurate. A boundary layer develops. Jet free inside, the velocity is parallel to the boundary in the layer
€
pcocoon = pjet + 4 pjetΓ 2 sin[tan−1( dzdr⊥
)− tan−1( zr⊥)]
€
β j =ηΓ j
2
1+ ηΓ j2β h
€
ηj2 =
L jρ∗c
3Σ
z
r
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II: Shock breakoutII: Shock breakoutIs the first radiative phase: hot non-relativistic material is released on the stellar surfaceRamirez-Ruiz et al. 2002
MacFadyen et al. 1999Zhang et al. 2003
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III: Shocked JetIII: Shocked JetThe jet in this phase is heavily affected by the transversal collimation shocks.
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IV: Unshocked JetIV: Unshocked JetThe evolution can be computed analogously to the confined jet geometry but now the cocoon pressure decreases with time.
€
dQ
dt= −ρ cocoonΣ
cs
€
pcocoon = pjet + 4 pjetΓ 2 sin[tan−1( dzdr⊥
)− tan−1( zr⊥)]
€
θ j =θ0
1+Kpcocoon
The opening angle of the jet grows
with time
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Analytic vs. Numeric
Analytic vs. Numeric
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Analytic vs. Numeric
Analytic vs. Numeric
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Analytic vs. Numeric
Analytic vs. NumericCocoon pressure
and breakout time are very well reproduced.Jet opening angle works better for jet initially out of causal contact (due to hyper-relativistic approximations).Energy stored in the cocoon:
8x1050 vs. 9x1050
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Analytic ResultsAnalytic Results
The break-out opening angle is smaller for more massive and large stars
A jet with initial opening angle of 10o and =10 is propagated through polytropic stars of varying mass and radius. WR
PopIII
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Analytic ResultsAnalytic ResultsA jet with initial opening angle of 10o and =10 is propagated through polytropic stars of varying mass and radius. WR
PopIIIThe break-out time depends very mildly on the mass, so too the energy deposited into the star
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Analytic ResultsAnalytic ResultsAssuming β=0.3 is a good approximation in most cases.
As a consequence massive compact stars will NOT explode due to the jet propagation GRBs without SN?
Exploding Stars
Non exploding (no SN?)
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Numerical:
movies
Numerical:
movies
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Numerical:
movies
Numerical:
movies
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Numerical ResultsNumerical Results
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Numerical ResultsNumerical ResultsDifferent observers see GRBs dominated by a different phaseSmall angles are dominated by shocked jet.
Intermediate angles are dominated by unshocked jetLarge angles are dominated by cocoon
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Numerical ResultsNumerical Results
Precursor
Dead times
X-ray flash
X-ray flash
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SummarySummary A simple pressure balance explains some features of the jet/cocoon/star interaction and allows quantitative computations
Jet can propagate fast in very massive stars if compact (β~0.3 robust). PopIII GRBs?
Jet propagation takes place in 4 phases: 3 radiative
Cocoon = Precursor but we do not see shocked or un-shocked jet. Different observers are however dominated by different phases.
Even a constant luminosity at the base can produce very complex time histories at the stellar surface.
A simple pressure balance explains some features of the jet/cocoon/star interaction and allows quantitative computations
Jet can propagate fast in very massive stars if compact (β~0.3 robust). PopIII GRBs?
Jet propagation takes place in 4 phases: 3 radiative
Cocoon = Precursor but we do not see shocked or un-shocked jet. Different observers are however dominated by different phases.
Even a constant luminosity at the base can produce very complex time histories at the stellar surface.